Medion monitor backlight issue

[netdent]

Hi Looking for some help advice, I have a Medion MD20165 pc monitor that has a problem with the backlight, it comes on at first but will go out after a few mins! putting on and off again restores it again for varying amounts of time but mostly goes off after 2 to 5 minutes, was just going to replace the psu but having problems finding one, closest I got was this on-

http://www.ebay.co.uk/itm/1210047821...84.m1423.l2649

Which is almost identical but the numbers don't match up, any help would be most welcome, will post some pics of the psu/invertor

thanks Ronnie

[Behemot]

Re: Medion monitor backlight issue

I see those damn two-FETs-in-one-package…

Anyway, have a look for colder joints, may be it. Are most of those caps Chemi-Cons?

[tom66]

Re: Medion monitor backlight issue

Those caps are Hermei (, with the fake Panasonic vent.

[netdent]

Re: Medion monitor backlight issue

I see those damn two-FETs-in-one-package…

Anyway, have a look for colder joints, may be it. Are most of those caps Chemi-Cons?

thanks for the reply, already had a good look at the solder joints with a magnifier they all look ok, this screen has barley been used! any other ideas?

thanks Ronnie

[Behemot]

Re: Medion monitor backlight issue

Those caps are Hermei (, with the fake Panasonic vent.

Ah yes, sorry, got it confused, it's Rubycon-like vent, but brown, that's, eh, does not Nichicon have some similar caps?

[netdent]

Re: Medion monitor backlight issue

I'm thinking not capacitors? anyone help me out please?

Ronnie

[tom66]

Re: Medion monitor backlight issue

Ah yes, sorry, got it confused, it's Rubycon-like vent, but brown, that's, eh, does not Nichicon have some similar caps?

No, Rubycon is "K", and Nichicon is "+". Sometimes Rubycon goes with a cross like pattern, but with overhang on each leg, and only on their larger caps.

[Behemot]

Re: Medion monitor backlight issue

But this looks like K to me...

[netdent]

Re: Medion monitor backlight issue

Found this which I think would work? but looks like only shipped in US I'm in UK

http://www.shopjimmy.com/aoc-6204-79...t-inverter.htm

[Behemot]

Re: Medion monitor backlight issue

For that money is that even worth it? You can get used one for that here. So you either repair it, or disassemble and e. g. sell display alone. No point in buying just board when yo ucan have whole monitor for that.

[netdent]

Re: Medion monitor backlight issue

For that money is that even worth it? You can get used one for that here. So you either repair it, or disassemble and e. g. sell display alone. No point in buying just board when yo ucan have whole monitor for that.

It is worth the effort as it's a 21.5" multi-touch screen and they are still expensive!

[Behemot]

Re: Medion monitor backlight issue

I see…

[netdent]

Re: Medion monitor backlight issue

Anyone any ideas on this?

thanks Ronnie

[netdent]

Re: Medion monitor backlight issue

Small update, in desperation I replaced some of the caps this made no diffrence BUT! if I go into the menu and select eco mode which reduces brightness it will work longer and instead of going black it constantly flickers the backlight? might not help much but maybe..........

Ronnie

[selldoor]

Re: Medion monitor backlight issue

When the Backlight goes off does the power led stay blue or whatever colour it is when its on? and can you still see a dark image on screen - try with a flashlight.

[selldoor]

Re: Medion monitor backlight issue

I know you have checked the joints but I would be inclined to resolder the inverter transformer, the blue high voltage caps along the top of Pic1 and the big resistor in that area. Are you able to try pluging the backlights into another working supply - it could be the wiring to the lamps (although I note you say its not been used much)- can you also check they are not arcing out to the frame.

[netdent]

Re: Medion monitor backlight issue

I know you have checked the joints but I would be inclined to resolder the inverter transformer, the blue high voltage caps along the top of Pic1 and the big resistor in that area. Are you able to try pluging the backlights into another working supply - it could be the wiring to the lamps (although I note you say its not been used much)- can you also check they are not arcing out to the frame.

Hi thanks for the reply, yes light stays blue and image is still on the screen with no backlight.

I have reflowed the joints on the invertor and the blue caps at the edge of board and also the 2 transistors on heat sinks, not got anything to hand to power the lights, no sign of any arcing that I can tell but not easy to see as everything has to be enclosed in the tin box to power it on!

with the reduced eco setting it is now staying on for a very long time and has not flickered in the last few hours

thanks Ronnie

[budm]

Re: Medion monitor backlight issue

I still think it can be the lamp wire connection, it if it is hst touching the end of the lamp, it can stay on some time for hours before it quits. I experience that before. You do not want to open up the screen to check the lamps, then make yourself 4 lamps for testing.
Bad lamp assemblies:
http://s807.photobucket.com/albums/y...klight%20lamp/
Test lamps:
http://s807.photobucket.com/albums/y...g%20old%20CFL/

Lamp tester:
http://www.ebay.com/itm/Universal-CC...item41606f799e

[netdent]

Re: Medion monitor backlight issue

Thankyou, I will try and make some test lamps I have plenty damaged laptop screen to use

Ronnie

[netdent]

Re: Medion monitor backlight issue

The Ebay link? could this be used to power the lights permanently?

thanks Ronnie